This invention relates to methods for shipping pneumatic tires typically for use with very large vehicles such as earthmoving vehicles.
The pneumatic tires, which are the subject of the method of the present invention, are very large tires (greater than 120 inch outside diameter (OD)) generally designed for use on very large vehicles, generally off-the-road (OTR) vehicles such as earthmovers and large-capacity mining trucks (e.g., 300 short tons or more). These very large tires and vehicles are generally utilized at long-term mining or construction sites such as rock quarries, mines, foundries, major tunnel/roadway construction, dams/dikes, and the like. The very large vehicles are generally too large to transport to the work site normally, and are therefore often shipped in pieces to the work site where the pieces are assembled/welded together for use. As modern construction vehicles have evolved to large and larger sizes, their tires have also grown to the point where conventional shipping of the tires becomes difficult. For example, an existing design of 360 ton (32,6530 kg) truck requires pneumatic tires of 154 inch diameter (3.91) meter which is considered to be the maximum size tire reasonably possible to ship by rail or roadway means in the United States. Tire weight is another consideration, as very large tires can weigh 8,000 pounds (3,628 kg) to 15,000 pounds (6,803 kg) or more per unmounted tires. The industry would like to progress to even larger, 400 ton (362,812 kg) or 450 ton (408,163 kg) trucks with correspondingly larger tires of 160 inch (4.07 meter) diameters or more. Depending on local limitations of shipping means (such as tunnel/bridge clearances and roadway weight limits), even somewhat smaller ones of the xe2x80x9cvery large tiresxe2x80x9d may pose significant problems, and may therefore require extraordinary transport means such as by helicopter.
Another problem is storage of the very large tires at the work site. As tires become larger, more and more space is required for storage. Also, if operating conditions are particularly harsh, or if shipping of replacement tires xe2x80x9con demandxe2x80x9d is not practical, then increased numbers of spares must be stocked, further increasing the storage space needed. Furthermore, some job sites require different tread designs for different operating conditions. For example, wide treads with deep cleats may be needed for muddy conditions. Given the time consuming nature of the existing tire-changing methods, changing tires to obtain optimum tread patterns is not always feasible.
Finally, even if driving tires and steering tires on the very large vehicles are the same overall size, the tread patterns of the two types of tires need to be different for most effective operation. This again adds to the number of replacement tires, which must be stored at a work site.
There is therefore a need for a method of shipping very large tires that allows for the employment of more conventional shipping means, and there is a desire to reduce the work site storage requirements as well as to improve the efficiency of the very large tire changing process.
Although tires having replaceable treads are known in automotive/motorcycle and conventional truck tire applications, it is not until recently that tread belt tires have been developed to meet the unique requirements of very large pneumatic tires for very large vehicles. U.S. patent application Ser. No. 09/424,089 entitled TIRE WITH IMPROVED REMOVABLE TIRE TREAD BELT to Rayman, having a common assignee with the present invention, of which this invention is related, discloses a tire with an improved removable tire tread belt for use on large earthmover vehicles. This tread belt tire (also called a xe2x80x9ctrack belt tirexe2x80x9d) xe2x80x9cis constructed of a removable tread belt assembly mounted to the outer circumferential surface of an inflatable tire carcass. A unique track belt design restrains the track from expanding while simultaneously improving the secure mounting of the track to the carcass and providing improved penetration protection. Also, the improved track belt will maintain a flatter tread profile which in turn will improve tread life and durability.xe2x80x9d
A predecessor version of removable treads or tracks for very large tires is discussed in U.S. Pat. No. 4,351,380, wherein certain prior art track belt tire assemblies comprise a plurality of ground-engaging xe2x80x9cshoesxe2x80x9d spaced about the periphery of the supporting structure. The heavy loads on the xe2x80x9cshoesxe2x80x9d result in great stresses being developed that sometimes lead to premature tire failure. The U.S. Pat. No. 4,351,380 is directed to an improved track belt assembly which comprises a plurality of shoes spaced about the periphery of a load-supporting structure and secured to a reinforcing belt structure disposed on the side of the shoe opposite the ground-engaging side thereof
A body of prior art exists for tires with removable tread belts (see, for example, U.S. Pat. Nos. 3,897,814; 3,224,482; 3,087,526; and British Patent G.B. 2,073,109). However these patents were directed toward the addressing of various issues related to tires used by predominantly roadway vehicles such as automobiles and trucks. Examples of these issues include: varying cord spacing to reduce wear of the outer tread belt edge for xe2x80x9cenhanced service life and lower manufacturing costxe2x80x9d; improving transverse bending for xe2x80x9cbetter riding comfort and improved road holding abilityxe2x80x9d; and linking separate tread rings to improve xe2x80x9croad -holding capabilities and . . . silent riding.xe2x80x9d Accordingly, the prior art has varied the quantity, shape, placement and spacing of tread rings, reinforcing belts, inextensible cords, and interlocking grooves in the tire carcass and tread belt, but these variations have not been adequate to address the special needs of off-the-road vehicle tires, nor of very large tires in general.
The concept of a two piece tire construction provided a novel way which the tread belt and the tire carcass could be separately shipped and stored. U.S. Pat. No. 6,324,814 describes a unique way of compressing the tread belt against a spacer creating an elongated oval for shipping. Additionally the carcass could be compressed to facilitate shipping, each component being separately restrined for shipment.
While this approach facilitates inventory problems of different tread types, and can more compactly permit shipping. The present invention permits an even more efficient method of shipping such tires.
There are still unsolved problems, relating to a pneumatic tire and tread belt assembly, concerning shipping, storage, inventory, and changing of very large tires on very large vehicles.
The present invention relates to an improved method for shipping and storing very large pneumatic tires, which are used on very large vehicles such as earthmover vehicles. Very large tires of conventional construction are sometimes over 13 feet (4 meter) in height and approximately 8,000 pounds (3,628K) to 15,000 pounds (6,803K) in weight and proposed very large truck designs require even larger tires. The size and weight of the very large conventional tires presents significant problems in shipping, storage and tire changing.
The method of shipping very large diameter tires having unrestrained diameters (OD) over 120 inches (3.05 meters) had the step of holding at least one diameteral size of the tire 10 in a compressed state thereby reducing the distance from the unrestrained diameter (OD) of over 120 inches to a maximum distance (H) or less as measured across at least two opposing diameteral sides of the tires. The compressed distance H being at or below standard widths for commercial trucking. The compressed state tire can be placed on a commercial standard width flat bed trailer or within a commercial standard size shipping container for shipment. If only one side of the tire is compressed the assembly may be shipped vertically allowing the compressed side to act as a base assuming the height is sufficiently small to allow bridge clearance. Alternately, the tires may be shipped horizontally laying on the sidewalls and stacked vertically.
If the tires are sufficiently large, the tires may be restrained along two diametrically opposed sides thus compressing the encircled carcass across two sides. In this case the tires can be shipped standing vertical and stacked horizontally assuming sufficient vertical clearance is maintained in most containers and closed trailers the vertical height is between 90 and 110 inches general while the width is 90 to 96 inches for standard width trailers and containers. Naturally the elongated oval shape means the longest dimension is increased by an amount at least as much as the amount of diametrical compression and in such a case the recommended way to ship the tire in the compressed state is to orient the elongated length in the lengthwise direction of the trailer or container whether shipped vertically or horizontally.
Preferably the compression of the carcass is such that the elongated sides of the tread belt are substantially straight sided or convexly curved. Alternatively, the tread belt can be compressed beyond straight sided resulting in a somewhat bow tie shape. Naturally, the amount of compression is recommended to be generally as small as needed to comply with the shipping constraints.
In another aspect the tire is compressed by holding four diametrical sides thereby reducing the opposite sides to form a substantially rectangular or square tire for shipping.
According to one aspect of the invention, the very large tires have a removable tread belt and the tread belt is shipped encircling the tire carcass. The removable tread belt is held in a compressed state for shipping, thereby having a significantly-reduced diameter for ease of shipping by using the tire carcass as deformable spacer.
According to this aspect of the invention, the deformable carcass spacer is provided for the compressed tread belt forming the tread belt into an elongated oval shape. The assembly of oval shaped tread belt encircling the compressed tire in a reduced dimensional state for shipping can create gaps between one or both ends of the elongated oval tread belt and the carcass.
According to an aspect of the invention, at least some of the tread belts are stored in a compressed state, thereby further reducing storage space requirements.
Other objects, features and advantages of the invention will become apparent in light of the following description thereof